This invention relates to a process for drying compositions containing derived protein-containing compositions and particularly byproducts obtained from concentrating whey protein by means of ultrafiltration or gel filtration and the dried product obtained thereby.
Because of the increasing requirement for protein sources throughout the world, various processes have been recently developed to extract protein from whey. Particular reference is made to the Dienst Attebery patent, Reissue Pat. No. 27,806, which discloses a method of separating protein from cheese whey by means of a molecular sieve resin, more commonly known as gel filtration. Also in active use is the technique of ultrafiltration to separate and concentrate the protein from the whey. The development of the separation techniques has also raised further processing problems. The byproducts from these processes are not easily adaptable to present known techniques of material handling.
In the processing of cheese whey by molecular sieve resin, a low molecular weight fraction (about 5-10% solids) is obtained which has a solids composition of mainly lactose and minerals with residual protein. The solids in this low molecular weight fraction can be described more particularly by the following typical chemical analysis.
______________________________________ Lactose, % 40-50 Minerals, % 25-35 Protein (N .times. 6.38), % 15-20 Lactic Acid, % 7-10 Citric Acid, % 3-6 Fat, % less than 1 Moisture less than 5 pH 6.6-7.2 ______________________________________
Similarly, the use of ultrafiltration provides a permeate which is high in minerals and lactose. The solids in the permeate can be described more particularly by the following typical chemical analysis.
______________________________________ Lactose, % 70-80 Minerals, % 10-15 Protein, (N .times. 6.38), % 4-8 Fat, % less than 1 Moisture less than 5 pH 6-7 ______________________________________
After removing the lactose by normal lactose crystallization procedures, the now delactosed permeate contains from about 40% to about 45% lactose, from about 25% to about 35% ash and from about 8% to about 12% protein (TKN.times.6.38). However, the total Kjeldahl nitrogen (TKN) is a measure of all of the nitrogen in the system (protein as well as non-protein nitrogen), and this is an approximation of the total protein present. While the delactosed permeate is indicated to have 8-12% protein (TKN.times.6.38), more than 60% of this protein is based on non-protein nitrogen, i.e., derived protein and amino acids. Derived protein is defined as a decomposition product of proteins that is intermediate in complexity of structure between proteins and amino acids (Hackhs' Chemical Dictionary, 3rd Ed.).
Two primary problems have been associated with the conventional drying of the low molecular weight fraction and the permeate. First of all, conventional drying techniques cannot be utilized as effectively due to undesirable particle adherence to the walls. Particle adherence to the drier walls tends to cause general ineffective drier operation as well as burnt and large particles in the final product.
The second problem associated with these products is the undesirably high level of hygroscopicity exhibited by these products. The products, particularly delactosed permeate, rapidly pick up moisture from the air. The hygroscopicity of the product adversely affects fluid characteristics of the product such that bagging becomes difficult to accomplish using common industrial equipment. Also, the undesirable level of hygroscopicity tends to detract from the potential use of this product in food applications. Once the package is opened, the dried particles immediately absorb moisture and cake.
It is also known to utilize the permeate and delactosed permeate in the formation of an egg albumen extender. In assignee's copending application Ser. No. 970,688, now U.S. Pat. No. 4,238,519 issued Dec. 9, 1980 the disclosure of which is incorporated herein by reference, there are disclosed egg albumen extenders comprising at least 65% by weight on a dry solids basis of a derived protein-containing composition from plant or animal sources wherein said derived protein-containing composition has a molecular weight of less than 20,000, a total Kjeldahl nitrogen content of from about 0.45% to about 2.1% of which at least 60% of the nitrogen is non-protein nitrogen, and from 0% to about 30% of a whipping aid, in combination with a member selected from the group consisting of gelatin, gelatin and a water soluble polyphosphate, a gum, and mixtures thereof. It has been found that these products are also difficult to dry when prepared from the liquid byproduct solution. Even in the presence of drying aids such as starch, these products are still difficult to dry. In drying blends of whey by-product, additives and starch, it was noticed that the use of the preferred high solids content feed to the spray dryer produced a product of high density. However, the high density product caked after packaging. It is theorized that the high density product does not cool and therefore cakes by fusing, particularly when immediately packaged. While cooling, such as on a conveyor, might assist in overcoming the fusion problem, the product is hygroscopic and can cake from moisture absorbed from the atmosphere during cooling. While cooling equipment with a controlled atmosphere may overcome the caking problems, the equipment would introduce expense and a time loss prior to packaging. Dry blending cannot be accomplished due to the difficulties in drying the byproduct solution before blending.
An improved process for drying a mineral containing aqueous protein solution is disclosed in U.S. Pat. No. 3,840,996. In this patent, the low molecular weight byproduct fraction from the gel filtration of the whey is admixed with inorganic drying agents selected from the group consisting of tricalcium phosphate, dicalcium phosphate, kaolin, diatomaceous earth, silica gel, calcium silicate hydrate, or mixtures thereof and spray dried. This product is useful in flavor-enhancing various foods.
In accordance with assignee's copending application Ser. No. 6,817, the drying of mineral containing delactosed or deproteinized whey byproduct solutions can be improved by mixing from about 5% to about 50% casein or alkali metal caseinates with the solution and codrying the solution. However, the high cost of casein and caseinates make this process economically unattractive.
Low D.E. carbohydrates are taught to be useful as carriers and drying aids for many dehydrated foods such as dry peanut butter, dried citrus powders, spray-dried oils, wine flavors, apple juice powder, vegetable powders, and sweetening agents (Low-D.E. Corn Starch Hydrolysates, D. G. Murry and L. R. Luft, Food Technology, March 1973, pp. 32-40). Tapioca dextrin is taught to be useful for a spray drying adjuvant (National Starch Product Bulletin No. 428).
It has now been found that the drying problems of compositions containing deproteinized mineral-containing whey solutions obtained as the byproducts of whey protein concentration and additives can be alleviated.